1. Field of the Invention
The present invention relates to an improved method and apparatus for underwater device leak detection in a hydraulic system or device that includes a hydraulic ram. More particularly, the present invention relates to a method of detecting leaks (e.g. broken or cut hose or leaking seal or fitting) in an underwater hydraulic system that uses an underwater hydraulic cylinder.
2. General Background of the Invention
In the offshore oil and gas industry, there are certain hydraulic devices that are needed in order to complete jobs in an underwater environment. A hydraulic shear is employed to conduct salvage operations. Such a hydraulic shear is lowered to a seabed area, for example several hundred feet (meters) deep. In this offshore environment, leakage of hydraulic oil has a profoundly disastrous effect on the environment.
Therefore, there exists a need for a simple and straightforward yet workable solution to the problem of leakage of hydraulic fluid from devices that are used in a marine environment.
It is not only important that a leak of hydraulic fluid be detected. It is further important that the hydraulic device be immediately disabled so that leakage is limited to a very minimal quantity.
Patents have issued that relate generally to the detection of leakage. One example is the Brandt patent (U.S. Pat. No. 5,748,077). The Brandt patent (U.S. Pat. No. 5,748,077) shuts down the hydraulic system if the leak is detected and notifies individuals in the area that a leak has occurred. The leak detection system has sensors for measuring hydraulic system parameters and a computer for detecting abnormalities in the system based on values returned by the sensors. Sensors used include an rpm pickup, a pressure transducer, a flow meter and a hydraulic fluid level and temperature switch. Outputs of the sensors are analyzed by the computer to determine if the hydraulic system has a leak. If a leak is detected, the computer sends response signals to a device for engaging or disengaging the prime mover from the hydraulic pump and to another device for actuating a valve to stop hydraulic fluid flow from the reservoir. The computer may also send indicator signals to a display console for activating a warning light, a buzzer or a display.
The Cass patent (U.S. Pat. No. 4,471,797) provides a hydraulic circuit breaker reset device. The system includes a pump, reservoir and an actuator system. The hydraulic circuit breaker is arranged to compare fluid flow to and from the actuator system and to shut off this flow in the event the flow to the actuator system is greater than the flow returning from the actuator system by more than a predetermined differential, thereby indicating a leakage condition. A hydraulic circuit breaker reset device is hydraulically connected to the actuator system and to the circuit breaker. When the circuit breaker is in a shut off condition, the reset device continuously pressure tests the actuator system. If the pressure in the actuator system increases to indicate the absence of fluid leakage, the reset device responds to the pressure increase in the actuator system to provide a reset signal to the circuit breaker. After the circuit breaker is reset to its normal operating position, a timing piston returns the reset device to its normal operating condition.